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Programming
4.1.3 Occlusion (Blockage) Test
An occlusion test (also called a blockage test or a gross pressure
loss test) is a method of testing in which pressure in an open
product must drop below a set level for a pass condition.
Occlusion tests are generally used to evaluate products that have
openings to check for potential blockages or obstructions of the
flow path. Generally, occlusion tests are used on parts which are
not large enough to work well with a back-pressure test.
All occlusion test parameters are the same as in a pressure decay
test. The reject maximum and reject minimum is the reverse of a
pressure decay leak test. Rather than expecting the part to hold
pressure we now expect the pressure to flow to atmosphere. In an
occlusion test, a good part is expected to leak (or flow) so the
reject value must be greater than a given value.
For simplicity, the definitions of all the parameters or how to
program will not be explained here. For more information see the
explanation of a pressure decay test.
Results in Pressure Decay or Flow Rate (Volume/time)
The results of an occlusion test are usually displayed in pressure
drop. The tester can also display the result in units of cubic
centimeters per minute (ccm). Simply enter the volume of the part
under test to activate the conversion to ccm flow rate. When zero
is entered as the product volume, the calculation to ccm is
disabled and the results are displayed as pressure loss in units of
psig.
Occlusion Test Examples
The same pneumatic circuit employed in pressure decay testing is
used in occlusion testing; only the programming is different.
Thanks to the commonality of test circuits, it is possible to
conduct pressure decay tests followed by occlusion tests. This is
easy to accomplish with Sprint iQ’s program linking ability.
